As this article is being written, outdoor marijuana planting season is starting in Europe and North America. One of the most impressive outdoor strains growers rely on is a nearly-pure Sativa photoperiod variety from Holland’s legendary Serious Seeds.

We’ve been fortunate to grow almost all Serious Seeds strains, one of only two heritage Dutch seed companies still offering high-quality strains that satisfy old-school growers and modern consumers.

Serious Seeds’ founder Simon gave us a wonderful interview about the strain, called Serious 6, but let’s start with a brief strain description.

Serious 6 was produced by years of breeding science decades ago using genetics that now aren’t available anywhere else, including a rare cut of killer Durban Poison and a tiny amount of Indica-ish genetics used to slightly restrain the blazing Sativa characteristics.

As with all of Simon’s strains that have been around for 20 or more years, he constantly tweaks strains to increase potency, yield, and resilience while still retaining the strain’s unique qualities.

Serious 6 produces 2-3 phenos, but differences between phenos are minor, mostly in color of pistils (pink versus white), bloom phase duration, and scent rather than in yield, size, or high.

Simon engineered Serious 6 to be extremely sensitive to very small changes in the amount of light per day so it would finish early enough for European growers in cold, rainy climates where sunlight and climate go wrong early in autumn or even late summer. Growers have long favored Serious 6 because it finishes so fast, faster than almost all other Sativas.

They love its heavy yields, resistance to molds, pests, and diseases, pink flowers, lemon-rose scent, and mind-sharpening, body-energizing high. Indoor growers who accommodate the strain’s cultivation needs love it for the same reasons outdoor growers do.

Simon is developing a newer version, called Serious 7, and we recommend you read the very informative full strain description on the Serious Seeds website about both 6 and 7. You can also email Simon via the website to ask about strains that work best for your high and your location. He is very helpful and smart.

Now let’s talk to Simon…

GMP: Simon, thanks for taking the time. Let’s begin by having you explain what makes a strain ideal for outdoor growing.

SIMON: Whether a strain is appropriate for outdoor growing depends a lot on where you want to grow it. Serious Seeds is based in The Netherlands, which does not have wonderful weather or enough direct sunlight hours for most strains to be grown outdoors, especially not strains which do best indoors under lights.

So in Holland, some strains are called indoors because we cannot grow them outside. We can only grow strains that finish before nasty autumn weather kicks in around the end of September with high wind gusts, hard rains, mist in morning and evening, little sunlight.

Overly wet, windy conditions when plants are finishing flowering cycle usually means gray mold and other pathogens. That’s why I make outdoor strains that resist pathogens and will be harvest-ready before bad weather comes. Those strains we call outdoor when living in Holland.

But if you live in the south of France or California, just two examples, you can grow a lot of types we call indoor strains indoors or outdoors. Basically, outdoors and indoors are arbitrary designations. It all depends on the specific climate and sunlight hours conditions where you would grow.

GMP: What and where are the best conditions for Serious 6 outdoors?

SIMON: Pretty much the same outdoor cannabis growing conditions in Holland are found in Germany, almost all of Denmark, the UK except the most northern parts of Scotland, Canada, and other parts of North America roughly up till the 55th degree North parallel, Serious 6 plants finish before bad weather. Above the 55th North latitude it depends on how the weather plays out. You might get lucky.

Because Serious 6 withstands high humidity without succumbing to gray mold, it can be grown outdoors between 55th parallel (latitude) North and all the way down to the 55th parallel South, including very humid situations in the subtropics.

In very humid tropical situations many growers also choose Kali Mist. Both it and Serious 6 are near-pure Sativas that are much more resistant to molds and mildews compared to genetics from Afghanistan and other dense Indicas which are bred into almost everything nowadays (think skunk for instance).

Growers all over the world from the tropics to colder climates tell us that Serious 6 and Kali Mist do very well for them outdoors.

I personally have grown the Serious 6 outdoors for more than a decade and it was very resistant to pathogens and insect attackers.

Of course, the Dutch climate doesn’t favor spider mites and other pests that commonly plague cannabis in other climates. We’re lucky not to have to even think about using chemicals. The problems we experience outdoors here come from slugs, or herbivores like rabbits, deer, and even cows!

This plant is a great choice for guerrilla growers. It’s such a sturdy, voracious grower that it outpaces weeds and needs no maintenance as long as roots have access to water, soil is fertile and plants get sufficient direct sun every day because shade is not a good place to grow this Sativa strain.

GMP: Given that Serious 6 is a fast grower, is there time to do topping and training to increase yield and shape plant profile and height?

SIMON: Yes, some growers clip and/or tie plants to keep them low so neighbors don’t see them. Serious 6 is very vigorous and sturdy and easily reaches heights of three meters or more, which is like a small tree.

That’s one reason I don’t germinate Serious 6 seeds for outdoor growing before June 1st—I don’t want to have to top and clip them, and by giving a shorter grow season, they develop a natural profile but not too tall like trees.

This plant is a great choice for guerrilla growers because it’s a beast of a plant that outgrows weeds and needs no maintenance as long as roots have access to sufficient water and nutrients.

GMP: Let’s talk about the yield and high.

SIMON: We figured out how to retain pure Sativa characteristics in a fast-finishing plant that has much heavier harvests than growers expect from Sativa.

People tell us Serious 6 tests at around 18-19% THC, so younger growers used to 25-35% THC in new strains that are mostly Indica and Kush assume this means they won’t feel the high.

Actually, the cannabis high comes from a lot more than just the THC percentages, and Serious 6 has a magical high you feel very much without in any way feeling overwhelmed or paranoid.

Our growers tell us the high is stronger than almost all other outdoor Sativas, even ones that take twice as long to be harvest-ready.

The high is clear, thoughtful, stimulating, euphoric. It allows you to be happy and smile even on the worst day.

People love the taste and scent of Serious 6, which is dominated by limonene and other terps. If you’ve ever grown pure African Sativa, you will be somewhat familiar with its scent and high, and you’re sure to love Serious 6!

Author’s Note: Please check out our other articles about Serious Seeds’ strains here at Growing Marijuana Perfectly.

Simon is one of few seed breeders worldwide who for 40 years has used rare, proprietary genetics and uncompromising breeding standards to create award-winning strains.

What’s more, his business ethics are impeccable. In a world of cannabis seeds sellers who are mostly unskilled pollen chuckers looking to make quick profits, Simon is an artist, a wizard, an honest, good person. There are few others like him. In the past two years, for example, he released several incredible strains based on a rare Mimosa cut.

Outdoor season is starting, and I receive my seeds from Serious within 1-2 weeks of ordering them. Serious 6 and 7 will put big smiles on your face this outdoor season.